During one century and a half, the Jesuits were the driven force in higher education, the sciences, and the arts in Río de la Plata. The inventory of their possessions, expropriated by the Spanish crown in 1767, is a witness to the material grandeur of their missions, colleges, and estancias; their spiritual heritage was equally immense.⁴ Debates about the organisation and contents of learning in Córdoba and Buenos Aires after the expulsion of the Society of Jesus from the Viceroyalty of Peru reflected the positive or negative responses toward its cultural legacy. In 1610, the Jesuits had founded a college in Córdoba, which in little more than a decade was granted the power of awarding degrees by Pope Gregory XV; it would eventually grow into the University of Córdoba, the intellectual powerhouse of the Society in Río de la Plata. Shortly after, they established the University of Chuquisaca in Charcas, Upper Peru (present-day Bolivia). These tended to be conservative institutions which taught philosophy, theology, civil and canon law; original inquiry about the natural world ( astronomy, natural history, materia medica, cartography) flourished in the freer atmosphere of the missions. As a consequence of the 1767 expulsion of the Jesuits from Spanish America, this world of “missionary science” would be irretrievably lost.

The ejection of the Jesuits from the Guaraní missions was the result of a long series of events. In the 1720s and 1730s, a protracted armed conflict erupted between the members of the Society of Jesus and the Spanish and creole landowners of Paraguay, who wished to release the Guaraní from the missions to use them in their own encomiendas (a system of forced labour); they also resented the Jesuits’ extensive landholdings and their efficient and profitable production of yerba mate (Paraguayan tea) of superior quality. The 1750 Treaty of Madrid, signed between Spain and Portugal, assigned the lands east of the Uruguay River (what is now Rio Grande do Sul in Brazil) to Portugal. This implied that the seven Jesuit missions in that area had to be moved west of the river. The armed Guaraní militias resisted but in the end lost what came to be known as the “ Guaraní wars”: the rebellion was crushed by a conjoint Spanish and Portuguese force in February 1756 and its leader, José (Sepé) Tiaragú was executed. The failed Guaraní uprising triggered a spate of anti-Jesuit literature that exploited the theme of the rich Jesuit “kingdom” of Paraguay and its rebellious attitude against the crown.⁵ The treaty was annulled in 1761.

Obeying Charles III’s order of 27 February 1767, Governor Francisco de Paula Bucareli commanded the expulsion of the Jesuits from the cities of Río de la Plata and from the Guaraní and Chaco missions. By March 1768 all of them had been dispatched to Europe. Those who were Spanish or Spanish-American ended up in Faenza or the Papal States; the rest (most of them German-speaking Jesuits) returned to their countries of origin. It should be noticed that “the Fathers from Paraquaria—brutally and stupidly—were not allowed to take with them the written materials that would have assisted them when in exile they wrote their numerous works.”⁶ At that time, there had been 457 Jesuits in Paraquaria: 295 Spanish, 81 born in Río de la Plata, 53 Germans, 17 Italians, four English, two from Peru, two Portuguese, one Greek, one French, and one Flemish.⁷ The large structure of Jesuit missionary work and learning, which it had taken a century and a half to build up, collapsed within a year. Their states, buildings, and libraries were from then on administered by the crown.

The Jesuits had been expelled from Portugal in 1759 and from France in 1764. In Spain, anti-Jesuit momentum came to a head with the “Esquilache riots,” a movement of revolt triggered by unpopular laws which took place in early 1766 and for which the Jesuits were held responsible (current opinion is that they were not). The accusation was spelled out in the Dictamen fiscal (1766) authored by Pedro Rodríguez de Campomanes, a public prosecutor of the Council of Castile. The document was a detailed exposition of the alleged damage inflicted on the state by the members of the Society of Jesus; one of its nine chapters dealt with the Guaraní missions.⁸ Campomanes and others contended “that the Jesuits had created in Paraguay a state within the state where the Indians lived in slavery and the Crown had no power.”⁹ The Guaraní wars and the subsequent international campaign of anti-Jesuitical books and pamphlets (much of which was instigated by the Portuguese minister Sebastião de Carvalho e Melo, Marquis of Pombal) were important factors contributing to the expulsion of the Jesuits from Spain.¹⁰

Magnus Mörner has argued that the ultimate cause of the expulsion should be sought in Charles III’s regalist tendencies and his efforts to concentrate power.¹¹ The “ Jansenist” position of some of Charles III’s ministers such as Campomanes and Pedro Abarca de Bolea, Count of Aranda, also fostered the anti-Jesuit animus of the crown.¹² In Bourbon Spain, “ Jansenist” (a name of abuse given to their opponents by the Jesuits) meant a person who envisaged a church dependent on the state and independent from Rome (something approximating Gallicanism); it had little to do with the theological questions of grace and predestination associated with Jansenius or with the moral stance and spirituality of seventeenth-century French Jansenists. At most, it expressed the desire for a more enlightened religion, free of superstition and of the most extreme forms of baroque popular piety. Jesuits defended the infallibility and supreme authority of the papacy over the universal Church (ultramontanism), the jurisdiction of the Church over against that of the state, and a style of religion impregnated by the values and spirit of the Counter- Reformation. It should be noticed that the more radicalised currents of the French Enlightenment did not cross the Pyrenees and if they did, their effect was marginal. During the reigns of Charles III and Charles IV Spain remained solidly Catholic; the conflicts that shattered the religious and learned world were internal dissensions within the Catholic Church.¹³ Something analogous could be said of the role played by Jansenism and Gallicanism in the suppression of the Society of Jesus by Clement XIV in 1773.¹⁴ Far from seeing the dissolution of the Jesuits as the consequence of the French Enlightenment, current opinion tends to consider it as a consequence of an opportunist “converge of convenience” among reformist and regalist rulers, Jansenist, and Gallican feeling.¹⁵ This complex state of affairs should be born in mind at the time of explaining the relationships between science and religion in colonial Río de la Plata.

The reductions (reducciones) formed the living heart of the complex of religious, economic and educational institutions which the Jesuits built up in Paraquaria. This religious province, configured in 1610, extended over present-day Argentina, Paraguay, Uruguay, part of Bolivia, and south-western Brazil.¹⁶ Over the course of 160 years, the Society of Jesus founded around one hundred missions. Eventually, many of them were destroyed, moved or merged. The core of the Jesuit Republic was constituted by the famous “33 towns,” in which, at the peak of their population curve in 1732, lived more than 140,000 Guaraní, a people of roaming agriculturalists.¹⁷ The number of Jesuits was comparatively small. By 1692 there were 249 of them in the province, of which 73 were in the missions.¹⁸ The main economic basis of the reductions were the cultivation and commercialization of yerba mate and cattle ranching; the colleges were supported by large estancias manned by African slaves (around 3,000 by 1767).¹⁹

The reductions had been designed to free the Guaraní from the system of encomienda which consisted of granting a Spaniard a number of aborigines who worked for him in conditions of servitude, in exchange for being supported and Christianized; the system lend itself to all kind of abuses. The mission towns allowed the Jesuit Fathers to segregate the natives from Spanish colonial society, thereby preserving them from what the Jesuits saw as the scandalous way of life of the settlers, and also enabled the Fathers’ religious instruction of the natives. This paternalistic system, which worked beyond any initial expectations, prompted the emergence of a rich hybrid culture. The printin...